Question

我编写了一个工作正常的RPS程序。我唯一的问题是它必须永远持续下去，直到用户的输入是＆＃34;停止＆＃34;。我尝试使用while循环执行此操作但是我得到一个奇怪的输出，一直要求用户的输入。我知道我的一个错误是我需要在while循环中提示输入，但是我将如何开始使用while循环。

import java.util.*;
public class Navairps
{
   public static void main(String[] args)
   {
      Scanner input = new Scanner(System.in);
      Random rand = new Random();
      play(input,rand);
   }
   //outputs the description and rules of the game
   public static void description()
   {
      System.out.println("Using this app you can play Rock-Paper-Scissors game against the computer. When played between");
      System.out.println("two people, each person picks one of the three options at the same time, and the winner");
      System.out.println("Is determined. The program should randomly choose one of the three options, then prompt for the");
      System.out.println("user's selection. At that point, the program reveals both choices and print a");
      System.out.println("Statement indicating if the user won, the computer won, or if it was a tie. Continue playing until the");
      System.out.println("user choose to stop. Then print the total number of the games played, total wins, total losses, and");
      System.out.println("total ties.");
      System.out.println("Ready, Set, Go\n");
      System.out.println("your choices");
      System.out.println("\tRock");
      System.out.println("\tPaper");
      System.out.println("\tScissors");
      System.out.println("\tstop");
   }
   //generates a random number (0-2) for the computer selection
   public static String computerRandom(Random rand)
   {
      int computer = rand.nextInt(3);
      String computerInput=("");
      switch (computer)
      {
         case 0: computerInput = "rock";
                 break;
         case 1: computerInput = "paper";
                 break;
         case 2: computerInput = "scissors";
                 break;
      }
      return computerInput;   
   }
   //gets the users choice via Scanner class and returns it, must check if input is valid
   public static String userInput(Scanner input)
   {
      System.out.print("Enter your choice: ");
      String choice = input.nextLine();
      choice = choice.toUpperCase();
      return choice;     
   }
   //initiates the game, allows user to keep playing, keeps track of score
   public static void play(Scanner input, Random rand)
   {
      description();
      int wins=0;
      int draws=0;
      int losses=0;
      String choice = userInput(input);
      while (!choice.equals("STOP"));
      {
         String computerChoice = computerRandom(rand);
         System.out.println("Computer selected: " + computerChoice);
         computerChoice = computerChoice.toUpperCase();
         System.out.println("You selected: " + choice);
         if (computerChoice.equals(choice))
         {
            System.out.println("There is a tie");
            draws++;
            //add 1 to ties
         } 
         if (computerChoice.equals("ROCK") && choice.equals("SCISSORS"))
         {
            System.out.println("Oh No, you lost");
            losses++;
            //add 1 to losses
         }
         if (computerChoice.equals("SCISSORS") && choice.equals("ROCK"))
         {
            System.out.println("Hurray! You won");
            wins++;
            //add 1 to wins
         } 
         if (computerChoice.equals("PAPER") && choice.equals("ROCK"))
         {
            System.out.println("Oh No, you lost");
            losses++;
            //add 1 to losses
         } 
         if (computerChoice.equals("ROCK") && choice.equals("PAPER"))
         {
            System.out.println("Hurry! You won");
            wins++;
            //add 1 to wins
         } 
         if (computerChoice.equals("PAPER") && choice.equals("SCISSORS"))
         {
            System.out.println("Hurry! You won");
            wins++;
            //add 1 to wins
         } 
         if (computerChoice.equals("SCISSORS") && choice.equals("PAPER"))
         {
            System.out.println("Oh No, you lost");
            losses++;
            //add 1 to losses
         } 
      }
      /*if (choice.equals("stop"));
      {
         System.out.print("come back soon");
      }*/
   }
}

Answer 1

这是do{} while()循环的教科书示例。而不是使用while循环，更改您的代码如下：

public static void play(Scanner input, Random rand)
   {  
      ...
      do {
         choice = userInput(input);
         String computerChoice = computerRandom(rand);
         ...
      } while (!choice.equalsIgnoreCase("STOP"));
   }

这将解决您的问题。

但是，当您发出STOP命令时，您可能不希望游戏再次计算随机值，因此您可能需要额外的 if -condition来阻止计算机播放进一步：

if (!choice.equalsIgnoreCase("STOP")){
         String computerChoice = computerRandom(rand);
         System.out.println("Computer selected: " + computerChoice);
         ...
}

请注意，除了使用 if -statement之外，您还可以使用break来摆脱循环：if (choice.equalsIgnoreCase("STOP")) break;

Answer 2

在应用程序/程序的加载时启动while循环，然后使用break;结束if条件下的while循环

Answer 3

这里至少有两个问题

停止命令为STOP而不是小写stop
choice = userInput(input)仅在循环外设置一次

正如之前在一些评论中所述，do {} while()是可行的方法。

请注意，您可以使用equalsIgnoreCase()代替equals()，因此您无需将所有内容转换为大写。

岩石纸剪刀程序，而循环

3 个答案: